# ermm i need help with factorising quadratics and quadratic sequences i tried to understand it but i cant can someone help me with this?

i keep getting confused with the squared part and the other part my exam is in june and i really want to get an a

Posted Tue 31st May, 2011 @ 22:18 by Stephanie

alright thanks guys :))x

i will look at them now :D

Answered Wed 1st June, 2011 @ 13:57 by Stephanie

FACTORISING A QUADRATIC MEANS PUTTING INTO 2 BRACKETS

1.     THE STANDARD FORMAT FOR A QUADRATIC EQUATION IS: ax² + bx + c    e.g x² + 3x + 2 = 0²

2.     FACTORISING METHOD WHEN “a=1”

3.     ALWAYS REARRANGE INTO THE STANDARD FORMAT: “ax² + bx + c = 0”

4.     WRITE DOWN THE 2 BRACKETS WITH THE x’s IN: (x     )(x     )=0

5.     THEN FIND 2 NUMBERS THAT MULTIPY TO GIVE “c” BUT ALSO ADD/SUBTRACT TO GIVE “b”

6.     PUT THEM IN THE BRACKETS AND CHECK THAT THE SIGNS WORK PROPERLY OTHERWISE YOU WILL GET THE WRONG ANSWER

WHEN a DOES NOT =1

E.G SOLVE 3x² + 7x=6 BY FACTORISING

1.     REARRANGE IT TO THE STANDARD FORMAT

2.     THEN BECAUSE a = 3 THE 2 x TERMS WILL HAVE TO MULTIPLY TO GIVE 3x² SO THE BRACKETS WILL BE: (3x    )(x     )=0

3.     NOW LOOK AT ALL THE PAIRS OF NUMBERS THAT WILL MULTIPLY WITH EACH OTHER TO GIVE c AND ADD/SUBTRACT TO GIVE b SO EITHER 1 X 6 OR 2 X 3

4.     NOW TRY ALL THE POSSIBILITIES IN THE BRACKETS AND ELIMINATE WHICH EVER ONES YOU DON’T NEED.

5.     (3x   1)(x    6) multiplies to give 18x & 1x which also add/subtract to give 17x or 19x

6.     (3x   6)(X    1) multiplies to give 3x & 6x which also add/subtract to give 9x or 3x

7.     (3x   3)(x    2) multiplies to give 6x & 3x which also add/subtract to give 9x or 3x

8.     (3x   2)(x    3) multiplies to give 9x & 2x which also add/subtract to give 11x 0r 7x

9.     So (3x   2)(x    3) is the combination that gives b=7

10.  Now fill in the +/- signs so that the combination adds up to +7 so that brackets are (3x -  2)(x  +  3)

11.  To check expand the brackets to see if you end up with the original equation!

HOPE THIS HELPS:D

Answered Tue 31st May, 2011 @ 23:05 by SONIKA

aww thanks that really helped :))x i need to learn this!

Answered Tue 31st May, 2011 @ 23:22 by Stephanie

Easier way is look at my videos that teach you this!

Answered Wed 1st June, 2011 @ 00:47 by Star Pupils Tuition

i've got a couple of resources on this if that's going to help you :) **

Answered Wed 1st June, 2011 @ 08:11 by Kelly:)

IVE GOT AN AMAZING! POWERPOINT ON MANIPULATING QUADRATICS!!!

Answered Wed 1st June, 2011 @ 12:47 by Georgina